Designated hitter and part-time first baseman David Ortiz left Wednesday afternoon's game in the fifth inning after experiencing tightness in his lower back.

The Red Sox certainly can't afford to lose a bat like Big Papi's. He's hitting .323 with 24 home runs and 78 RBI.

Ortiz first experienced some back discomfort Monday and sat out Tuesday's game. However, he was back in the lineup and manning first base on Wednesday.

Ortiz did appear to tweak his back during a fifth-inning strikeout and was replaced by Mike Napoli.

“It kind of grabbed me a little bit in my first at-bat. I was trying to fight through it. It’s not anything bad. It’s just a little tight. The manager just decided to pull me out because I wasn’t feeling good. I’ll probably be fine. I’m not really concerned about it. I think I’ll be fine.”

According to WEEI.com, Ortiz said the long travel day from Boston to San Francisco on Monday was probably the cause.

“I came out of the airplane like that. I can’t really tell [what caused it]. But I feel it when I’m playing or when I’m hitting. I’m telling you, I don’t know who did this schedule. It probably is a Yankees fan.”